Spektrum SR3000 antenna length

[BrianG]

Wow, this is taking me back to school days! Can't remember the specifics, but antenna length DOES matter. And it has to be full-wave, half-wave, quarter-wave, and so on. This is for optimum receiving potential.

For transmitters, the proper length is imperative! The wrong length messes up the SWR (standing wave ratio) and the power that's supposed to go to the antenna gets dumped back in the circuits. Ever mess with an old CB and SWR meter?

[Arct1k]

http://www.spektrumrc.com/Products/F...D=SPM1200#faq4

Does the receiver have an antenna? If so, how long is it? Return to Top
Yes, the stock antenna is 8.5” long making mounting the antenna easy. What’s more, if you prefer a shorter antenna, you can carefully cut the Spektrum receiver antenna to just 3.6” – and not lose any performance. This way, you can keep the antenna inside the body.


So 8.5-3.6 = 4.9" to cut off!

[starscream]

I accidentily cut the antenna on my SR3000 but I haven't noticed any ill effects. The antenna wire is now only 2.2" from the case (stubby) and it works fine. I haven't tried running it real far but 75 ft is no problem at all.

i have mine under the reciever box lol, so i have no length i can still go a 1/4 mile or so

[Serum]

I was just looking for the length of the antenna's myself (for the 2.4Ghz receivers)

here is what i found out; the length of these HF signals must be 1/4th, 3/4th or 5/4th of the wave length (and so on)

the wavelength of the 2.4 Ghz signal is 125mm

the 3.6" is 3/4th of the 125mm.

I don't know how your receiver is constructed, but i assume the antenna straw is directly mounted onto the case of the receiver, which is in straight line with the PCB;

The length of the antenna is the length of the entire antenna, including the small bit it travels through the house.

Hope this helps. I was looking for an answer on how long the 2.4 Ghz antenna's need to be, and this 3.6" they claim confirms what i've read somewhere else.

[Serum]

the 8.5" it's long is 7 times the wave-length of the 2.4Ghz signal.

[Arct1k]

So any multiple of 1.21 should be fine...

[redshift]

Aha.... maybe I know more about it than I thought- the whole wavelength thing.. Thanky for the info.

I stripped the piece I cut off, it is single-run standard wire.

I can't do a real range check yet, I have other bugs to look for and address first, but I'll try to keep you posted.

[redshift]

Ok just an update, I've had it 400-500 feet out and no issues, but I am NOT using a BEC, that may make a big difference.

So no range problems with a properly shortened antenna.

If you are using BEC and have range loss, you might swap your BEC for a Rx pack and see what happens...

Just in case anyones wondering. I had my FASST RX apart today and its antenna plugs in. Its not directly soldered to the circuit board.